Lately after having sex with my g/f, the second round we can't have it because she claims that its painful. This is really disturbing me and I don't why.

Leave her alone. It is PAINFUL for her.

Hey. I don't know for sure what may cause it. My Girlfriend Can climax but can't have an actual orgasm. After she reaches that point she says it is to painful to go on or do anything else. So, you aren't the only one in the boat. If you do find out what might be happening please let me know.

This is an adult board, folks.

What exactly does that mean Choux?

I have a friend that told me she was experiencing this with her boyfriend. Perhaps she is saying 'it hurts' when really a lot of friends have said to me that they can't handle the sense of orgasm... and haven't actually orgasmed before.
I hope this helps :).

What are the ages of the OP and his girlfriend, please?